1. Field of the Invention
This invention relates generally to window frames and flanges.
2. Prior Art
FIG. 1 is a sectional view showing a conventional aluminum window frame 10 attached to a wall 11 in a typical installation. Wall 11 includes on its interior a drywall 12 and a casing 13. A liner 14 is attached to the perimeter of the window opening. Sidings 15 are attached in front of a subsiding 16, which is attached to a header 17. Window frame 10 includes a vertical nailing flange 18 inserted between siding 15 and subsiding 16, and a horizontal member 19 extending forwardly from the lower edge of nailing flange 18. Rain water, as indicated by the dashed arrow, hitting horizontal member 19 can seep under siding 15, but is prevented by nailing flange 18 from entering wall 11.
Aluminum windows are often replaced by vinyl windows, which are structurally very different. A common replacement method involves collapsing the aluminum window frame, and attaching a vinyl window frame 20 in front of liner 14 and below siding 15, as shown in FIG. 2. Caulking 21 is applied to a joint between vinyl window frame 20 and siding 15 to prevent water entry.
However, caulking 21 is sometimes improperly applied. Even when caulking 21 is properly applied, it will eventually fail and separate from window frame 20 and/or siding 15, and provide a path for rain water to seep into the inside of the window, as indicated by the dashed arrow.
As shown in FIG. 3, another common replacement method involves cutting siding 15 and subsiding 16 to expose the nailing flange of the original aluminum window frame, removing the aluminum window frame, adding a wood trim filler 22 under siding 15 and subsiding 16, and attaching a vinyl window frame 23 under liner 14 and filler 22. Although a vertical nailing flange 24 is provided on some vinyl window frames, it is positioned below caulking 21, so that it cannot prevent rain water seepage when caulking 21 fails. A path for rain water seepage to the inside of the window is indicated by the dashed arrow.